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    <title>ShellCheck: SC3032 – In POSIX sh, coproc is undefined.</title>
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    <h1>SC3032 – ShellCheck Wiki</h1>
    <a href="https://github.com/koalaman/shellcheck/wiki/SC3032">See this page on GitHub</a>
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    <h2 id="in-posix-sh-coproc-is-undefined">In POSIX sh, coproc is
undefined.</h2>
<h3 id="problematic-code">Problematic code:</h3>
<div class="sourceCode" id="cb1"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb1-1"><a href="SC3032.html#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="co">#!/bin/sh</span></span>
<span id="cb1-2"><a href="SC3032.html#cb1-2" aria-hidden="true" tabindex="-1"></a><span class="bu">coproc</span> nc shellcheck.net 80</span></code></pre></div>
<h3 id="correct-code">Correct code:</h3>
<p>Either switch to Bash:</p>
<div class="sourceCode" id="cb2"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb2-1"><a href="SC3032.html#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="co">#!/usr/bin/env bash</span></span>
<span id="cb2-2"><a href="SC3032.html#cb2-2" aria-hidden="true" tabindex="-1"></a><span class="bu">coproc</span> nc shellcheck.net 80</span></code></pre></div>
<p>or try to write your script in a POSIX compatible way using named
pipes.</p>
<h3 id="rationale">Rationale:</h3>
<p>Your script uses a shell feature not supported by the shebang. Either
rewrite the script to be portable, or change the shebang to explicitly
require a shell like Bash.</p>
<p>There is no simple substitution for a coproc, though many use cases
can be rewritten via redirection to named pipes
(<code>mkfifo</code>).</p>
<h3 id="exceptions">Exceptions:</h3>
<p>None</p>
<h3 id="related-resources">Related resources:</h3>
<ul>
<li>Help by adding links to BashFAQ, StackOverflow, man pages, POSIX,
etc!</li>
</ul>
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    <p style='font-size: 80%'><a href="../index.html">ShellCheck</a> is a static analysis tool for shell scripts. This page is part of its documentation.</p>
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